A typical alternating-current surface discharge type panel used as a plasma display panel (hereinafter referred to as “panel”) has many discharge cells between a front plate and a back plate that are faced to each other.
The front plate has the following elements:                a plurality of display electrode pairs disposed in parallel on a glass-made front substrate; and        a dielectric layer and a protective layer for covering the display electrode pairs.Here, each display electrode pair is formed of a pair of scan electrode and sustain electrode. The back plate has the following elements:        a plurality of data electrodes disposed in parallel on a glass-made back substrate;        a dielectric layer for covering the data electrodes;        a plurality of barrier ribs disposed on the dielectric layer in parallel with the data electrodes; and        phosphor layers disposed on the surface of the dielectric layer and on side surfaces of the barrier ribs.        
The front plate and back plate are faced to each other so that the display electrode pairs and the data electrodes three-dimensionally intersect, and are sealed. Discharge gas containing xenon is filled into a discharge space in the sealed product. Discharge cells are disposed in intersecting parts of the display electrode pairs and the data electrodes. In the panel having this structure, ultraviolet rays are emitted by gas discharge in each discharge cell. The ultraviolet rays excite respective phosphor layers of red, green, and blue to emit light, and thus provide color display.
A subfield method is generally used as a method of driving the panel. In this method, one field period is divided into a plurality of subfields, and the subfields at which light is emitted are combined, thereby performing gray scale display.
Each subfield has an initializing period, an address period, and a sustain period. In the initializing period, initializing discharge occurs, and a wall charge required for a subsequent address operation is formed on each electrode. The initializing operation includes an initializing operation (hereinafter referred to as “all-cell initializing operation”) of causing initializing discharge in all discharge cells and an initializing operation (hereinafter referred to as “selective initializing operation”) of causing initializing discharge in a discharge cell having performed sustain discharge.
In the address period, address discharge is caused in a discharge cell where display is to be performed, thereby forming a wall charge. In the sustain period, a sustain pulse is alternately applied to the display electrode pairs formed of the scan electrodes and the sustain electrodes, sustain discharge is caused in the discharge cell having performed address discharge, and a phosphor layer of the corresponding discharge cell is light-emitted, thereby displaying an image.
Of the subfield method, a new driving method where light emission that is not related to gray scale display is minimized and the contrast ratio is improved is disclosed in patent document 1, for example. In this driving method, the initializing discharge is performed using a gradually varying voltage waveform, and the initializing discharge is selectively applied to the discharge cell having performed sustain discharge.
Specifically, for example, in the initializing period of one of a plurality of subfields, an all-cell initializing operation of causing discharge in all discharge cells is performed. In the initializing period of the other subfields, a selective initializing operation of initializing only a discharge cell having performed sustain discharge is performed. As a result, the light emission that is not related to the display is determined only by light emission following the discharge of the all-cell initializing operation, and an image of high contrast can be displayed.
In this driving method, the number of all-cell initializing operations is restricted. Therefore, the initializing operation becomes unstable, and a malfunction (hereinafter referred to as “false lighting”) can occur that causes sustain discharge in the discharge cell where address discharge has not been caused. Therefore, a driving method for stabilizing the initializing discharge by providing an unusual charge erasing part in the all-cell initializing period is disclosed in patent document 2, for example.
The screen size and definition of the panel have been recently increased, and study has been performed to improve the light emitting efficiency of the panel by increasing the partial pressure of xenon in the discharge gas filled into the panel. However, fining the discharge cell and increasing the efficiency of it elongate the discharge delay, and further the discharge is apt to become unstable. When the initializing operation becomes unstable, the false lighting is further apt to occur, and the image display quality can be significantly reduced. Such phenomenon is apt to occur when the panel temperature is low.    [Patent document 1] Japanese Patent Unexamined Publication No. 2000-242224    [Patent document 2] Japanese Patent Unexamined Publication No. 2005-326612